When a power semiconductor device is designed, a structure of a junction terminal portion for securing main breakdown voltage is important. For example, the power semiconductor device including a MOS power transistor such as an insulated gate bipolar transistor (IGBT) secures the main breakdown voltage by a RESURF, a guard ring, a field plate or the like. However, these structures have a problem that when a size of the junction terminal portion is reduced by decreasing a width of the junction terminal portion or by decreasing a depth of a diffusion layer in the junction terminal portion to shrink the size of circuits, it is difficult to secure the main breakdown voltage.